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Updated: Jun 13, 2026
Anteromesial Temporal Lobectomy for Medically Intractable Temporal Lobe Epilepsy: An Operative Study
Published on: August 15, 2025
How common is brain atrophy in patients with medial temporal lobe epilepsy?
Leonardo Bonilha1, Jordan J Elm, Jonathan C Edwards
1Division of Neurology, Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina 29425, USA. bonilha@musc.edu
Purpose:
It is unclear whether extrahippocampal brain damage in patients with medial temporal lobe epilepsy (MTLE) is a homogeneous phenomenon, as most data relates to the average volume reduction in groups of patients. This study aimed to evaluate where and how much atrophy is to be expected in an individual patient with MTLE.
Methods:
High-resolution T(1) magnetic resonance imaging (MRI) was obtained from 23 consecutive patients with unilateral MTLE and from a matched control group. Parametric tests of voxel-based gray matter volume evaluated mean regional atrophy in MTLE compared with controls. Gray matter images were then submitted to a voxel by voxel calculation of the fitted receiver operating characteristic (ROC) curve area, plotting the sensitivity versus 1-specificity for a binary classifier (MTLE vs. controls). The area under the curve (AUC) was calculated for each voxel and a resulting three-dimensional map of gray matter voxel-wise AUCs was obtained.
Results:
On average, patients with MTLE showed atrophy in the ipsilateral hippocampus and on a limbic network. Elevated AUC was demonstrated in the ipsilateral hippocampus and medial temporal lobe, the ipsilateral thalamus and occipitotemporal cortex, the ipsilateral cerebellum, the cingulate, the contralateral insula, and the occipitoparietal and dorsolateral prefrontal cortex.
Conclusion:
This study suggests that the medial temporal lobe, occipitotemporal areas, the cerebellum, the cingulate cortex, the ipsilateral insula, and thalamus are more likely to be atrophied in randomly selected patients with MTLE. Structures such as the orbitofrontal cortex, the contralateral medial temporal areas and insula, the putamen, and the caudate may be atrophied, but not as consistently.
Insights
Extrahippocampal brain damage in medial temporal lobe epilepsy (MTLE) is not uniform. This study identifies specific brain regions, including the medial temporal lobe and cerebellum, that are commonly atrophied in individual MTLE patients.
Area of Science:
- Neuroimaging
- Epilepsy Research
- Brain Atrophy
Background:
- Medial temporal lobe epilepsy (MTLE) is a common epilepsy syndrome.
- Extrahippocampal brain damage in MTLE is not fully understood, with most studies focusing on group averages.
- Individual variability in atrophy patterns requires further investigation.
Purpose of the Study:
- To determine the specific locations and extent of brain atrophy in individual patients with MTLE.
- To assess the homogeneity of extrahippocampal brain damage in MTLE.
Main Methods:
- High-resolution T1-weighted MRI scans from 23 MTLE patients and controls.
- Voxel-based analysis of gray matter volume to identify regional atrophy.
- Receiver Operating Characteristic (ROC) curve analysis at the voxel level to map atrophy probability.
Main Results:
- Patients with MTLE exhibited atrophy in the ipsilateral hippocampus and limbic network on average.
- Elevated atrophy probability (AUC) was found in the ipsilateral hippocampus, medial temporal lobe, thalamus, occipitotemporal cortex, cerebellum, cingulate, contralateral insula, and occipitoparietal/prefrontal cortex.
- Voxel-wise ROC analysis provided a detailed map of individual atrophy likelihood.
Conclusions:
- The medial temporal lobe, occipitotemporal areas, cerebellum, cingulate cortex, ipsilateral insula, and thalamus are frequently atrophied in MTLE patients.
- Other regions like the orbitofrontal cortex and basal ganglia may show atrophy but less consistently.
- This study provides a more individualized understanding of brain atrophy patterns in MTLE.
